This invention is directed to the art of media handling, in general, and methods and apparatus for converting non-continuous media handling devices into continuous media handling devices, in specific. Typically, the media comprises sheet material in the form of paper sheets.
A common method of sheet handling comprises the use of a high capacity top-sheet pick-up device, commonly known as a high capacity top-sheet feeder (hereinafter "HCTSF") to feed sheets from a vertically disposed stack of sheets found on a incrementally vertically movable table, to a down stream location. In particular, the uppermost sheet of the stack is picked off (i.e., separated), using a top-sheet pick-up device, for example, a vacuum pick-up located in the HCTSF, and the table then constantly and incrementally raised to maintain the uppermost sheet close to the top-sheet pick-up device for separation and removal of the top-sheet from the stack.
We have found problems with this arrangement. For example, when the stack of sheets on the table has been completely fed, the HCTSF (and any downstream machinery) must be stopped, the table lowered, a new stack of sheets placed on the table, and the HCTSF (and any downstream machinery) re-started. Thus, during this stack replenishment period, no sheets are being fed to the downstream machinery, rendering the HCTSF both non-continuous, and inefficient, in operation.
Furthermore, in this arrangement, the stack of sheets on the movable table is often in the range of 12-18 inches high. Stacks this high become unpredictable and hard to manipulate. For example, typically, the toner (or ink) distribution on sheets is uneven because the sheets will not have printed matter entirely thereon, i.e., the sheet will not be totally black. Thus, each individual sheet will be thicker in the area on which it has printed matter. As more and more sheets are stacked upon each other, these thicker portions multiply in effect to the point where the top surface of the sheet stack becomes uneven (non-planar). This makes it hard for a rigidly mounted top-sheet pick-up device to properly separate the top-sheet. Accordingly, a method by which this problem could be solved was searched for. While the prior art solution involved the manipulation of carefully positioned weights on the top of the sheet stack, this was a difficult solution to implement and a better solution was needed.
Accordingly, there is room for improvement within the art.